Or so it seemed until the 1950s, when collector Forest Sweet, who had accumulated six stray leaves (a leaf being a single two-sided page), deduced they came from Washington's original.

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Which is why it matters so much that scientists have, indeed, made progress toward identifying the genes that determine how many leaves a four-leaf clover has.

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It also replicated the randomness of nature: as one leaf moves, other leaves followed.

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Second, mistletoe sheds a lot of leaves, which add to the depth of the leaf litter in a wood.

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Grass-cutting ants occur in the Chaco region of north Argentina and Paraguay and belong to a subgroup of leaf-cutting ants that specialise in harvesting grass leaves.

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For her experiment she studied the inheritance of three traits: a maroon coloured leaf marking, a white V-shaped leaf mark pattern, and the production of hydrogen cyanide in damaged leaves, which is thought to be a defence against predators.

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The rare leaf is a part of the tobacco plant called the medio tiempo, taken from the upper leaves of the plant, but which not every plant produces, making it rare.

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The impression he leaves, however, is that he will pull us out as soon as he finds a shred of a fig leaf.

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